These were designed to facilitate testing but should provide enough function to be useful in other contexts. Only a subset of the functions of each peripheral is implemented, mainly due to the lack of a standard way to handle electrical connections (like GPIO pins).
Signed-off-by: Sarah Harris <s.e.har...@kent.ac.uk> --- include/hw/char/avr_usart.h | 93 +++++++++++ hw/char/avr_usart.c | 320 ++++++++++++++++++++++++++++++++++++ hw/char/Kconfig | 3 + hw/char/Makefile.objs | 1 + 4 files changed, 417 insertions(+) create mode 100644 include/hw/char/avr_usart.h create mode 100644 hw/char/avr_usart.c diff --git a/include/hw/char/avr_usart.h b/include/hw/char/avr_usart.h new file mode 100644 index 0000000000..467e97e8c0 --- /dev/null +++ b/include/hw/char/avr_usart.h @@ -0,0 +1,93 @@ +/* + * AVR USART + * + * Copyright (c) 2018 University of Kent + * Author: Sarah Harris + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, see + * <http://www.gnu.org/licenses/lgpl-2.1.html> + */ + +#ifndef HW_AVR_USART_H +#define HW_AVR_USART_H + +#include "hw/sysbus.h" +#include "chardev/char-fe.h" +#include "hw/hw.h" + +/* Offsets of registers. */ +#define USART_DR 0x06 +#define USART_CSRA 0x00 +#define USART_CSRB 0x01 +#define USART_CSRC 0x02 +#define USART_BRRH 0x05 +#define USART_BRRL 0x04 + +/* Relevant bits in regiters. */ +#define USART_CSRA_RXC (1 << 7) +#define USART_CSRA_TXC (1 << 6) +#define USART_CSRA_DRE (1 << 5) +#define USART_CSRA_MPCM (1 << 0) + +#define USART_CSRB_RXCIE (1 << 7) +#define USART_CSRB_TXCIE (1 << 6) +#define USART_CSRB_DREIE (1 << 5) +#define USART_CSRB_RXEN (1 << 4) +#define USART_CSRB_TXEN (1 << 3) +#define USART_CSRB_CSZ2 (1 << 2) +#define USART_CSRB_RXB8 (1 << 1) +#define USART_CSRB_TXB8 (1 << 0) + +#define USART_CSRC_MSEL1 (1 << 7) +#define USART_CSRC_MSEL0 (1 << 6) +#define USART_CSRC_PM1 (1 << 5) +#define USART_CSRC_PM0 (1 << 4) +#define USART_CSRC_CSZ1 (1 << 2) +#define USART_CSRC_CSZ0 (1 << 1) + +#define TYPE_AVR_USART "avr-usart" +#define AVR_USART(obj) \ + OBJECT_CHECK(AVRUsartState, (obj), TYPE_AVR_USART) + +typedef struct { + /* <private> */ + SysBusDevice parent_obj; + + /* <public> */ + MemoryRegion mmio; + + CharBackend chr; + + bool enabled; + + uint8_t data; + bool data_valid; + uint8_t char_mask; + /* Control and Status Registers */ + uint8_t csra; + uint8_t csrb; + uint8_t csrc; + /* Baud Rate Registers (low/high byte) */ + uint8_t brrh; + uint8_t brrl; + + /* Receive Complete */ + qemu_irq rxc_irq; + /* Transmit Complete */ + qemu_irq txc_irq; + /* Data Register Empty */ + qemu_irq dre_irq; +} AVRUsartState; + +#endif /* HW_AVR_USART_H */ diff --git a/hw/char/avr_usart.c b/hw/char/avr_usart.c new file mode 100644 index 0000000000..cb307fe23d --- /dev/null +++ b/hw/char/avr_usart.c @@ -0,0 +1,320 @@ +/* + * AVR USART + * + * Copyright (c) 2018 University of Kent + * Author: Sarah Harris + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, see + * <http://www.gnu.org/licenses/lgpl-2.1.html> + */ + +#include "qemu/osdep.h" +#include "hw/char/avr_usart.h" +#include "qemu/log.h" +#include "hw/irq.h" +#include "hw/qdev-properties.h" + +static int avr_usart_can_receive(void *opaque) +{ + AVRUsartState *usart = opaque; + + if (usart->data_valid || !(usart->csrb & USART_CSRB_RXEN)) { + return 0; + } + return 1; +} + +static void avr_usart_receive(void *opaque, const uint8_t *buffer, int size) +{ + AVRUsartState *usart = opaque; + assert(size == 1); + assert(!usart->data_valid); + usart->data = buffer[0]; + usart->data_valid = true; + usart->csra |= USART_CSRA_RXC; + if (usart->csrb & USART_CSRB_RXCIE) { + qemu_set_irq(usart->rxc_irq, 1); + } +} + +static void update_char_mask(AVRUsartState *usart) +{ + uint8_t mode = ((usart->csrc & USART_CSRC_CSZ0) ? 1 : 0) | + ((usart->csrc & USART_CSRC_CSZ1) ? 2 : 0) | + ((usart->csrb & USART_CSRB_CSZ2) ? 4 : 0); + switch (mode) { + case 0: + usart->char_mask = 0b11111; + break; + case 1: + usart->char_mask = 0b111111; + break; + case 2: + usart->char_mask = 0b1111111; + break; + case 3: + usart->char_mask = 0b11111111; + break; + case 4: + /* Fallthrough. */ + case 5: + /* Fallthrough. */ + case 6: + qemu_log_mask( + LOG_GUEST_ERROR, + "%s: Reserved character size 0x%x\n", + __func__, + mode); + break; + case 7: + qemu_log_mask( + LOG_GUEST_ERROR, + "%s: Nine bit character size not supported (forcing eight)\n", + __func__); + usart->char_mask = 0b11111111; + break; + default: + assert(0); + } +} + +static void avr_usart_reset(DeviceState *dev) +{ + AVRUsartState *usart = AVR_USART(dev); + usart->data_valid = false; + usart->csra = 0b00100000; + usart->csrb = 0b00000000; + usart->csrc = 0b00000110; + usart->brrl = 0; + usart->brrh = 0; + update_char_mask(usart); + qemu_set_irq(usart->rxc_irq, 0); + qemu_set_irq(usart->txc_irq, 0); + qemu_set_irq(usart->dre_irq, 0); +} + +static uint64_t avr_usart_read(void *opaque, hwaddr addr, unsigned int size) +{ + AVRUsartState *usart = opaque; + uint8_t data; + assert(size == 1); + + if (!usart->enabled) { + return 0; + } + + switch (addr) { + case USART_DR: + if (!(usart->csrb & USART_CSRB_RXEN)) { + /* Receiver disabled, ignore. */ + return 0; + } + if (usart->data_valid) { + data = usart->data & usart->char_mask; + usart->data_valid = false; + } else { + data = 0; + } + usart->csra &= 0xff ^ USART_CSRA_RXC; + qemu_set_irq(usart->rxc_irq, 0); + qemu_chr_fe_accept_input(&usart->chr); + return data; + case USART_CSRA: + return usart->csra; + case USART_CSRB: + return usart->csrb; + case USART_CSRC: + return usart->csrc; + case USART_BRRL: + return usart->brrl; + case USART_BRRH: + return usart->brrh; + default: + qemu_log_mask( + LOG_GUEST_ERROR, + "%s: Bad offset 0x%"HWADDR_PRIx"\n", + __func__, + addr); + } + return 0; +} + +static void avr_usart_write(void *opaque, hwaddr addr, uint64_t value, + unsigned int size) +{ + AVRUsartState *usart = opaque; + uint8_t mask; + uint8_t data; + assert((value & 0xff) == value); + assert(size == 1); + + if (!usart->enabled) { + return; + } + + switch (addr) { + case USART_DR: + if (!(usart->csrb & USART_CSRB_TXEN)) { + /* Transmitter disabled, ignore. */ + return; + } + usart->csra |= USART_CSRA_TXC; + usart->csra |= USART_CSRA_DRE; + if (usart->csrb & USART_CSRB_TXCIE) { + qemu_set_irq(usart->txc_irq, 1); + usart->csra &= 0xff ^ USART_CSRA_TXC; + } + if (usart->csrb & USART_CSRB_DREIE) { + qemu_set_irq(usart->dre_irq, 1); + } + data = value; + qemu_chr_fe_write_all(&usart->chr, &data, 1); + break; + case USART_CSRA: + mask = 0b01000011; + /* Mask read-only bits. */ + value = (value & mask) | (usart->csra & (0xff ^ mask)); + usart->csra = value; + if (value & USART_CSRA_TXC) { + usart->csra ^= USART_CSRA_TXC; + qemu_set_irq(usart->txc_irq, 0); + } + if (value & USART_CSRA_MPCM) { + qemu_log_mask( + LOG_GUEST_ERROR, + "%s: MPCM not supported by USART\n", + __func__); + } + break; + case USART_CSRB: + mask = 0b11111101; + /* Mask read-only bits. */ + value = (value & mask) | (usart->csrb & (0xff ^ mask)); + usart->csrb = value; + if (!(value & USART_CSRB_RXEN)) { + /* Receiver disabled, flush input buffer. */ + usart->data_valid = false; + } + qemu_set_irq(usart->rxc_irq, + ((value & USART_CSRB_RXCIE) && + (usart->csra & USART_CSRA_RXC)) ? 1 : 0); + qemu_set_irq(usart->txc_irq, + ((value & USART_CSRB_TXCIE) && + (usart->csra & USART_CSRA_TXC)) ? 1 : 0); + qemu_set_irq(usart->dre_irq, + ((value & USART_CSRB_DREIE) && + (usart->csra & USART_CSRA_DRE)) ? 1 : 0); + update_char_mask(usart); + break; + case USART_CSRC: + usart->csrc = value; + if ((value & USART_CSRC_MSEL1) && (value & USART_CSRC_MSEL0)) { + qemu_log_mask( + LOG_GUEST_ERROR, + "%s: SPI mode not supported by USART\n", + __func__); + } + if ((value & USART_CSRC_MSEL1) && !(value & USART_CSRC_MSEL0)) { + qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad USART mode\n", __func__); + } + if (!(value & USART_CSRC_PM1) && (value & USART_CSRC_PM0)) { + qemu_log_mask( + LOG_GUEST_ERROR, + "%s: Bad USART parity mode\n", + __func__); + } + update_char_mask(usart); + break; + case USART_BRRL: + usart->brrl = value; + break; + case USART_BRRH: + usart->brrh = value & 0b00001111; + break; + default: + qemu_log_mask( + LOG_GUEST_ERROR, + "%s: Bad offset 0x%"HWADDR_PRIx"\n", + __func__, + addr); + } +} + +static const MemoryRegionOps avr_usart_ops = { + .read = avr_usart_read, + .write = avr_usart_write, + .endianness = DEVICE_NATIVE_ENDIAN, + .impl = {.min_access_size = 1, .max_access_size = 1} +}; + +static Property avr_usart_properties[] = { + DEFINE_PROP_CHR("chardev", AVRUsartState, chr), + DEFINE_PROP_END_OF_LIST(), +}; + +static void avr_usart_pr(void *opaque, int irq, int level) +{ + AVRUsartState *s = AVR_USART(opaque); + + s->enabled = !level; + + if (!s->enabled) { + avr_usart_reset(DEVICE(s)); + } +} + +static void avr_usart_init(Object *obj) +{ + AVRUsartState *s = AVR_USART(obj); + sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rxc_irq); + sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->dre_irq); + sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->txc_irq); + memory_region_init_io(&s->mmio, obj, &avr_usart_ops, s, TYPE_AVR_USART, 8); + sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio); + qdev_init_gpio_in(DEVICE(s), avr_usart_pr, 1); + s->enabled = true; +} + +static void avr_usart_realize(DeviceState *dev, Error **errp) +{ + AVRUsartState *s = AVR_USART(dev); + qemu_chr_fe_set_handlers(&s->chr, avr_usart_can_receive, + avr_usart_receive, NULL, NULL, + s, NULL, true); + avr_usart_reset(dev); +} + +static void avr_usart_class_init(ObjectClass *klass, void *data) +{ + DeviceClass *dc = DEVICE_CLASS(klass); + + dc->reset = avr_usart_reset; + dc->props = avr_usart_properties; + dc->realize = avr_usart_realize; +} + +static const TypeInfo avr_usart_info = { + .name = TYPE_AVR_USART, + .parent = TYPE_SYS_BUS_DEVICE, + .instance_size = sizeof(AVRUsartState), + .instance_init = avr_usart_init, + .class_init = avr_usart_class_init, +}; + +static void avr_usart_register_types(void) +{ + type_register_static(&avr_usart_info); +} + +type_init(avr_usart_register_types) diff --git a/hw/char/Kconfig b/hw/char/Kconfig index 40e7a8b8bb..331b20983f 100644 --- a/hw/char/Kconfig +++ b/hw/char/Kconfig @@ -46,3 +46,6 @@ config SCLPCONSOLE config TERMINAL3270 bool + +config AVR_USART + bool diff --git a/hw/char/Makefile.objs b/hw/char/Makefile.objs index 02d8a66925..f05c1f5667 100644 --- a/hw/char/Makefile.objs +++ b/hw/char/Makefile.objs @@ -21,6 +21,7 @@ obj-$(CONFIG_PSERIES) += spapr_vty.o obj-$(CONFIG_DIGIC) += digic-uart.o obj-$(CONFIG_STM32F2XX_USART) += stm32f2xx_usart.o obj-$(CONFIG_RASPI) += bcm2835_aux.o +common-obj-$(CONFIG_AVR_USART) += avr_usart.o common-obj-$(CONFIG_CMSDK_APB_UART) += cmsdk-apb-uart.o common-obj-$(CONFIG_ETRAXFS) += etraxfs_ser.o -- 2.17.2 (Apple Git-113)
